GASPS-A Herschel Survey of Gas and Dust in Protoplanetary Disks: Summary and Initial Statistics
Artikel i vetenskaplig tidskrift, 2013
We describe a large-scale far-infrared line and continuum survey of protoplanetary disk through to young debris disk systems carried out using the ACS instrument on the Herschel Space Observatory. This Open Time Key program, known as GASPS (Gas Survey of Protoplanetary Systems), targeted similar to 250 young stars in narrow wavelength regions covering the [OI] fine structure line at 63 mu m the brightest far-infrared line in such objects. A subset of the brightest targets were also surveyed in [OI]145 mu m, [CII] at 157 mu m, as well as several transitions of H2O and high-excitation CO lines at selected wavelengths between 78 and 180 mu m. Additionally, GASPS included continuum photometry at 70, 100 and 160 mu m, around the peak of the dust emission. The targets were SED Class II-III T Tauri stars and debris disks from seven nearby young associations, along with a comparable sample of isolated Herbig AeBe stars. The aim was to study the global gas and dust content in a wide sample of circumstellar disks, combining the results with models in a systematic way. In this overview paper we review the scientific aims, target selection and observing strategy of the program. We summarise some of the initial results, showing line identifications, listing the detections, and giving a first statistical study of line detectability. The [OI] line at 63 mu m was the brightest line seen in almost all objects, by a factor of similar to 10. Overall [OI]63 mu m detection rates were 49%, with 100% of HAeBe stars and 43% of T Tauri stars detected. A comparison with published disk dust masses (derived mainly from sub-mm continuum, assuming standard values of the mm mass opacity) shows a dust mass threshold for [OI] 63 mu m detection of similar to 10(-5) M-circle dot. Normalising to a distance of 140 pc, 84% of objects with dust masses >= 10(-5) M-circle dot can be detected in this line in the present survey; 32% of those of mass 10(-6)-10(-5) M-circle dot, and only a very small number of unusual objects with lower masses can be detected. This is consistent with models with a moderate UV excess and disk flaring. For a given disk mass, [OI] detectability is lower for M stars compared with earlier spectral types. Both the continuum and line emission was, in most systems, spatially and spectrally unresolved and centred on the star, suggesting that emission in most cases was from the disk. Approximately 10 objects showed resolved emission, most likely from outflows. In the GASPS sample, [OI] detection rates in T Tauri associations in the 0.3-4 Myr age range were similar to 50%. For each association in the 5-20 Myr age range, similar to 2 stars remain detectable in [OI]63 mu m, and no systems were detected in associations with age >20 Myr. Comparing with the total number of young stars in each association, and assuming a ISM-like gas/dust ratio, this indicates that similar to 18% of stars retain a gas-rich disk of total mass similar to 1 M-Jupiter for 1-4 Myr, 1-7% keep such disks for 5-10 Myr, but none are detected beyond 10-20 Myr. The brightest [OI] objects from GASPS were also observed in [OI]145 mu m, [CII]157 mu m and CO J = 18 - 17, with detection rates of 20-40%. Detection of the [CII] line was not correlated with disk mass, suggesting it arises more commonly from a compact remnant envelope.
Författare
W. R. F. Dent
Atacama Large Millimeter-submillimeter Array (ALMA)
W. F. Thi
Rijksuniversiteit Groningen
Université Grenoble Alpes
I. Kamp
Rijksuniversiteit Groningen
J. P. Williams
University of Hawaii
F. Menard
Université Grenoble Alpes
S. Andrews
Harvard-Smithsonian Center for Astrophysics
D. R. Ardila
National Aeronautics and Space Administration (NASA)
G. Aresu
Rijksuniversiteit Groningen
J. C. Augereau
Université Grenoble Alpes
D. Barrado
Centro Astronómico Hispano Alemán de Calar Alto (CSIC-MPG)
Centro de Astrobiología (INTA-CSIC)
S. Brittain
Clemson University
A. Carmona
Université Grenoble Alpes
D. R. Ciardi
National Aeronautics and Space Administration (NASA)
W. Danchi
NASA Goddard Space Flight Center
J. Donaldson
University of Maryland
G. Duchene
Université Grenoble Alpes
University of California
C. Eiroa
Universidad Autonoma de Madrid (UAM)
D. Fedele
Max-Planck-Gesellschaft
C. A. Grady
Eureka Scientific
I. de Gregorio-Molsalvo
Atacama Large Millimeter-submillimeter Array (ALMA)
C. D. Howard
NASA Ames Research Center
N. Huelamo
Centro de Astrobiología (INTA-CSIC)
A. Krivov
Friedrich-Schiller-Universität Jena
J. Lebreton
Université Grenoble Alpes
René Liseau
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
C. Martin-Zaidi
Université Grenoble Alpes
G. Mathews
University of Hawaii
G. Meeus
Universidad Autonoma de Madrid (UAM)
I. Mendigutia
Centro de Astrobiología (INTA-CSIC)
B. Montesinos
Centro de Astrobiología (INTA-CSIC)
M. Morales-Calderon
Centro de Astrobiología (INTA-CSIC)
A. Mora
European Space Astronomy Centre (ESAC)
H. Nomura
Kyoto University
E. Pantin
Le Commissariat à l’Énergie Atomique et aux Énergies Alternatives (CEA)
I. Pascucci
University of Arizona
N. Phillips
Atacama Large Millimeter-submillimeter Array (ALMA)
C. Pinte
Université Grenoble Alpes
L. Podio
Atacama Large Millimeter-submillimeter Array (ALMA)
S. Ramsay
European Southern Observatory (ESO)
B. Riaz
University of Hertfordshire
P. Riviere-Marichalar
Centro de Astrobiología (INTA-CSIC)
A. Roberge
NASA Goddard Space Flight Center
G. Sandell
NASA Ames Research Center
E. Solano
Centro de Astrobiología (INTA-CSIC)
I. Tilling
University of Edinburgh
J. M. Torrelles
Universitat de Barcelona
B. Vandenbusche
KU Leuven
S. Vicente
Rijksuniversiteit Groningen
G. J. White
Open University
STFC Rutherford Appleton Laboratory
P. Woitke
University of St Andrews
Publications of the Astronomical Society of the Pacific
0004-6280 (ISSN) 1538-3873 (eISSN)
Vol. 125 927 477-505Ämneskategorier
Astronomi, astrofysik och kosmologi
DOI
10.1086/670826